1. Field of the Invention
The present invention relates to light diffusing sheets, and more particularly to a light diffusing sheet for use in, for example, a liquid crystal display (LCD).
2. Discussion of the Related Art
In a liquid crystal display, liquid crystal is a substance that does not itself radiate light. Instead, the liquid crystal relies on light received from a light source in order to provide displaying of images and data. In the case of a typical liquid crystal display, a backlight module powered by electricity supplies the needed light.
For improving a uniformity of brightness of output light, the backlight module generally needs a diffusing sheet. Referring to FIG. 1, a typical light diffusing sheet 10 is shown. The light diffusing sheet 10 includes a light diffusing layer 11 and a transparent plate 12. The light diffusing layer 11 has a matrix material 111, and a multiplicity of light diffusion particles 112 dispersed in the matrix material 111. The matrix material 111 is one of polycarbonate, polymethyl methacrylate, and polyester. The light diffusion particles 112 are polypropylene particles or glass beads, which are used for diffusing light that passes through the light diffusing sheet 10.
However, a difference between a refractive index of the matrix material 111 and a refractive index of the light diffusing particles 112 is small. This means the optical properties of the light diffusing particles 112 may be rather weak. For example, when an intensity of incident light varies significantly over different areas of the light diffusing sheet 10, the light diffusing particles 112 may not be able to sufficiently diffuse the light in order to output uniformly bright light from the light diffusing sheet 10. When this happens, a plurality of dark areas and/or a plurality of bright areas appear on an output surface of the light diffusing sheet 10.
Therefore, what is needed is to provide a new light diffusing sheet having improved light diffusing capability.